Process of producing polychrome photogravures and apparatus therefor.



JOHANNES TRAU, OF DRESDEN, GERMANY.

PROCESS OF PRODUCING POLYCHROME PHOTOGRA'VURES AND l.AIIIAIRAA'JJUS THEREFOR.

Specification of Letters Patent.

Patented Aug. 12,1913.

- Application iiled December 27, 1912. Serial No. 738,929.

To all whom z't may concern."

Be it known that I, JOHANNES TRAU, a citizen of the German Empire, and residing at Dresden, Germany, have invented a certain new and useful Improvedl Process of Producing Polychrome Photogravures and Apparatus Therefor, of which the following is a specification.

The subject-matter of my invention is a processV for producing polychrome photogravures 4by using subjective selection of colors, and particularly for producing a plurality of individual pictures on one large printing sheet, and valso apparatus for carrying the process into practice.

In my improved process the desired individual colors are selected, in known manner, by negative-retouching from one negative by means of any desired number of films of thin material, and then individually copied together with the negative on a separate i -printing plate. The film side of the negative is placed against the lm side of the printing plate, and the retouched surface of the covermg film is placed on the back of the lthin negative. Both the individual negative lms, carrying the picture lm proper, and

also the plate or film, on which the negative films are assembled, and the retouching films consist of materials which do not stretch in the presence of'moisture, e. g'. celluloid, collodion or the like. Bymeans of this process it is possible to make sharp colored photogravures from only one negative, yneither three-color photography nor the production of-several negatives being necessary. Further, my improved process enables a large number of individual pictures to be made simultaneously on one sheet Without some of these pictures bein ill defined. This is primarily due to the act that, according to my invention, the retouching films of celluloid or the like are placed on the lm side of the negative and are mounted together and heldfwith the negative when producing the negative retouches, while during the conjoint copying of the individual retouching films and the negative on the individual printing plates, the retouching Elm is placed lwith its retouched surface on the rear of the very thin negative film, the'lm side ofthe negative lying on the film side of the printing plate. The negative and retouching frame which is also used during the retouching. The negative arid also the retouching film can be stretched or adjusted alone, whereby again a quite exact fit is obtained.

The great advantages which'arise owing to the employment of only one negative, from which all the individual colors are selected by means of retouching films, without ill defined pictures being produced during the photogravure process, are sufliciently well known, so that they need not be enumerated. By means of the hereindescribed process not only can several separate pictures of postcard size bemfade with one negative, but, as is otherwise customary in the photogravure process, an entire sheet having as many as thirty-six separate post-cards.

The apparatus for carrying my process into practice substantially consists of two frames arranged one in the other and comprising two-part clamping rims, of which frames the inner serves for holding and stretching the negative, while the outer is employed for holding the retouching films.- Both the frames must have a device which admits of the retouching films being placed on .the two sides of the mounted negative and also admits of the retouching films being exactly adjusted relatively to the negative, it being immaterial whether they lie on the film side of the negative or on the rear.

One form .of such an apparatus is represented by way of example in the accompany ing drawing, wherein Figure l is a plan view showing a corner of such an apparatus; Fig. 2 is a section taken on the line a-a, Fig. 3 is a section taken on the line 5 6, and Fig. f1 is a section taken on the line c-c in Fig. l; Figs. 5 and 6 diagrammatically show the relative positions of the individual members when retouching and when copying, respectively.

Referring to the drawing, the apparatus comprises a box or case lewhose front wall possesses a suitable opening 2 corresponding.

in size to that of the surface to be exposed, while its rear wall 3 serves for closing the copying-case light-tight. Angular strips 4 are mounted in this case and serve for guiding two parallel two-part, displaceable clamping strips 5 and 6. Mounted on these two clamping strips are clamping screws 7 films are caused to register exactly'by the loo and 8, of which the latter, attached ftothe strips 6, pass through suitably' large holes 9 in thestrips 5. rllhe inner strips 6 are used for holding the negative.10,?whilltheouter strips serve for holding the retoucliing iilms: For this purpose lugsl2 are provided on the retouching films; these lugs extend' through recesses 13 -infthe innerclamping means of screws 14:, for which suitable-holeswill4 be provided '.in the-negative and in the-- lugs12 of the retouchingfilms. Thethick copying` glass 15 is held 4in .addition .inthe case 1, and lalso means, not shown,- are provided .fo'r :pressingthe printingplate 16 rmlyagainst the negative and securing it in its correct position. Wedges, springs andA other means generally used in copying frames are used for this purpose.

.My' improved process is carried into practice byA means of the above-'described apparatus as follows: The individual negatives of a .large number of Vsepara-te exposuresv are transferredfto a thin sheet ofcelluloid'in known manner by dissolvingthe negative film from. the .negative and transferringthe same to-.the'celluloid-oil. The series-negati-ve foil obtained in this manner is nowl fixed 1 in .the clamping .strips 6 Aover the: glassA 15 (Fig. 3) with the film` sideofthe-negative 10 top, By tighteningtherscrews 8 the nega tive is now stretched smooth. and then a .re-

touching;;foil. 11 is placed on .the negative. i

and its lugs 12 led throughV the recesses13 of the top part .of the strips 6 to the outer clamping strips 5. By tighteningthe screws.

7 this superposed retouching.. film is also stretched smoothpas shown in Fig. 5. When thishas been donethe retoucher begins his Work and by retouchingin full vand halfl tones selects that color which is desired. When the film 11 is retoucheoh'. e. when all theseparate small pictures of the negativehave been suitably treated on the retouching film, the film 11 is 'released from the clamping strips l5 and removed from the negative foil. The retoucher now proceeds in `like manner with the various other colors.4

When all the colors have beentreated in this manner thev printing plates are copied, as

Y manybeing copied as retouching films have been made.

` The copying itself is done as follows: One of the retouching films-is placed lunder the negative foil still held stretched by the clamping strips 6, the retouched 'surface of the film being placed against the negative Lesage@ foil. .The lugs of-this' retouching film are pushed' throughv the lower-recesses 13 in the lower part of the strips 6 and led to the clamping stripsl'-'and there secured. (Cf. Fig. 6). The retouching film is now adjusted exactly'corresponding to the negative foil by tightening the screws 7.

Iffolds-or waves have formed in the negativefoil or rinthe retouching film these can bereadily removed by adjusting the individual screws 7 and 8. Theretouching film and the negativefoil'areexactly adjusted to one :another .over the entire surface. The consequence is a sharp copy. It may here bementionedi thatthe printing plate 16 is placedfwith its-film side on the film side of the negative foil 10fand that this printingf plate is firmly pressed against the-.negative by-suitable means, e. g.v wedges, springs or the like, and held in the position in which it is placed..` As many i printing plates are madein this manner as colors have been re-v touched out of, thenegative. All these printingplates printed one over another result in the polychrome photogravure.

I claim 1. A process.- of producingv polychrom 'photogravures by-meansof subjective selection of colors, consisting. in placing the retouching. films, which are requisiteifor the various individual. colors, on the film side oi.` one-single-negative and selecting. the desired colorsgon the retouchinglms, in then placing the fretouching .films withtheir film sides against .the-back' 4of 'the negative lying .with

its lm side against. the printing plate, and. incopyingthe same, .both thenegative and:x

the retouchingfilms' consisting .of a material whichdoes not-.stretchfin the presence of variouszindividual colors, on the filxmside oli"` pne single negative and. selectingthe desired colors-'on ltheretouchingfilms, in then placing the retouchinglilms with their film sides against the vbackl .of the -negative lying. with' its filmside against theprintingplate, and

` producing'. polychrome in copyingthe same, boththe negative and the retouchingfilmsconsisting. of a material which-doesnotfstretchlin. the presence of moisture, the 2 negative being. stretched duringthe entireprocess and Vthe retouching films being. stretched tduringthe selecting and printing .operati-ons. i

` 3. .In .copying apparatus of the character described, thecombina-tion of inner stretch.- ing means, and Louter .stretching means-surf rounding.. thev same, the inner stretching.

means having openings directed toward the outerfstretching means. In copying apparatus of the character described, the combination with a case havlas ing an aperture in the front thereof, an n- In testimony whereof, I aizr my-sgnature ner stretching frame surrounding the aperin the presence of two Witnesses. ture, an outer stretching frame surrounding JOHANNES TRAU.

the inner frame, the inner frame having 5 openings directed toward the outer frame, Witnesses:

and a copying `glass normally held in the PAUL ARRAS, frame at the aperture. CLRE SIMON. 

